Graphics 出现异常的问题
class ColorPanel extends JPanel {
private int x = 30,y = 150,s = 0,e = 30;
public ColorPanel() {
drawarc();
}
public void drawarc() {
Graphics g = this.getGraphics();
g.setColor(Color.black);
g.drawArc( x, x, y, y, s, e );
s = e;
e += 30;
}
}
编译时没错,运行时g 出现空指针异常,
请问是怎么回事???